what truth are we talking about again? i´m a little lost here. what is yumi´s problem?

i believe in college, the two liked the same guy, and yumi told some rumors about female lead to make him back off of her. something like that, i could be wrong

Yumi was the FL's friend during college and she liked the guy that was apologizing to the FL on ch 57. That guy and the FL liked each other and were going out during college. Yumi spread around the rumor that the FL was sleeping with a college professor to get good grades. Because of those rumors, the guy broke off with the FL and she dropped out of college.
Later on the FL found out it was Yumi who created the rumor but by then the guy and Yumi were starting to go out so the FL didn't clear up the misunderstanding in fear of hurting the feelings of the guy because she was still in love with him. ┑(￣Д ￣)┍